Not applicable
The present invention pertains to compressed air blow guns. A blow gun to direct compressed air is a common tool used in factories, workshops and around trucks and other vehicles. Blow guns are frequently used around large truck tractors for the occasional need to use compressed air to expel debris and dust from a truck trailer or truck cab or sleeper and for other uses, as well as to inflate tires when the blow gun is equipped with an inflation chuck. The blow gun is coupled to an air hose coupled to a supply of compressed air which may be connected to the compressed air system of the truck tractor.
Adjustability of the length of the wand is a desirable feature in order to make the blow gun more versatile. An improvement for the standard fixed wand blow gun is shown in U.S. Pat. No. 5,832,974 to Jou which shows a blow gun with an adjustable wand. The prior art blow gun allows the wand to be adjusted by use of a threaded sleeve which urges clamping fingers into abutment with the outside of the wand of the blow gun. Adjustment of the extension of the wand requires the loosening of the threaded sleeve to a point which releases the clamping fingers and the retightening of the sleeve when the desired wand extension is made.
The present invention provides a blow gun with an extensible wand. Extension or retraction of the wand of the blow gun is accomplished by releasing the wand by rotation of a collar less than one half turn in either direction. The invention includes a handle having a trigger lever which opens a valve to permit compressed air from a source hose coupled to the handle to pass through the handle into an elongate wand on the end of which a nozzle may be mounted or alternatively a tire inflation chuck member may be mounted. The handle includes a barrel which serves as a storage housing for the wand when it is retracted. The wand through which compressed air may pass is adjustable in length by sliding it inwardly or outwardly longitudinally from the barrel of the handle. The wand may be extended to a desired length and locked into the particular extension position by use of an outer collar which is eccentrically rotatable upon an inner collar. The inner collar has a first section and an externally threaded extension which extends longitudinally from the first section. The extension is not coaxial with the first section but a longitudinal bore through the inner collar is coaxial with the first section and therefore is offset from the axis of the extension. The bore through the first section is internally threaded and sized to mount to the threads on the end of the barrel while the bore through the extension is smooth and is sized to permit the wand to be slid through it. The outer collar includes a threaded bore to receive the external threads of the extension of the inner collar. The threaded bore does not extend through the outer collar but rather longitudinally joins a smaller bore which is sized larger than the outer diameter of the wand. The axis of the smaller bore is slightly displaced from but parallel to the axis of the threaded bore of the outer collar. A ridge is formed longitudinally on the exterior of the outer collar to provide a lever to easily rotate the outer collar on the inner collar and to provide an indexing means.
Rotation of the outer collar less than one half of a turn will cause the bore of the outer collar to move such that the bore of the inner collar is no longer in registry with the small bore of the outer collar. Hence the outer collar forces the wand against the bore in the extension of the inner collar and thereby locks the wand in its then longitudinal position.
It is an object of the invention to provide a versatile blow gun which includes a wand which can quickly and simply be extended or retracted when released by less than a half turn of a collar surrounding the wand.
It is a further object of the invention to provide a blow gun with a variable length wand which may be extended or retracted without removing the wand from the handle of the blowgun.
It is also an object of the invention to provide an improved blow gun which allows for extension or retraction of the wand thereof without the use of numerous clamping parts mounted to the handle of the blow gun.